Instead of an ignition switch for a mechanical key used in a conventional vehicle, recent vehicle models use an electronic key system permitting engine startup by verifying an identification code stored in a computer mounted in the vehicle against an identification code recorded in an electronic key. The verification operation of the identification code in the electronic key and the computer is automatically performed by a wireless signal as a result of a driver being in proximity to the vehicle holding the electronic key.
After the driver stops the engine, alights from the vehicle and locks the door, engine startup is prohibited until the driver returns to the proximity of the vehicle and re-verifies the identification code.